ESS Standard Topic 6.1

Our Changing Atmosphere

Dynamic System

Has the Ability to Change

The Atmosphere as a Significant Idea

A dynamic system with inputs, outputs, flows and storage that has undergone changes throughout geological time

The Atmosphere

• A thin envelope of gas and suspended particles that surrounds the Earth

• Becomes increasingly thinner with distance away from Earth’s surface

• Held in place by the Earth’s gravitational pull

• It is the outer limit of the biosphere and its composition and processes support life on Earth.

The 4 main gases in the atmosphere

• Nitogen 78%

• Oxygen 21%

• Argon 1%

• CO_² 0.04%

Input and Output Wavelengths

Input - Shortwave Radiation

Output - Longwave Radiation

System

An assemblage of parts and the relationships between them that enable them to work together to form a functioning whole

Troposphere

The lowest and thinnest layer (10-15km) of atmosphere in constant motion, where all weather occurs. Gets colder as you go up and stops at the Tropopause.

Stratosphere

(40km thick) Composed of mostly dry stable air, So pollutants do not disperse and remain in the layer for long periods of time.

The Ozone Layer is found in the lower section of the Stratosphere and temperature gets warmer as you go up. Stops at the stratopause.

The other 3 layers of the atmosphere

3. Mesosphere (Temperature decreases)

4. Thermosphere (Temperature Increases)

5. Exosphere (Where satellites are found)

—pause (Between Atmospheric layers)

Separates the different —sphere layers and here temperatures are constant.

Change in pressure between Atmospheric layers

Decreases at an exponential rate, therefore less weight pushing down the higher you go.

Climate

How the atmosphere behaves over relatively long periods of time.

The Tricellular Model of atmospheric circulation

Differential heating of the atmosphere creating a tricellular atmospheric circulation that redistributes heat from the equator to the pole, creating distinct climate regions.

How does the Tricellular model of atmospheric circulation work?

Warm air rises at the equator, moves towards the poles, cools, and descends, forming three cells, and areas of high and low pressure. 

This making the equator cooler and northern latitudes warmer.

3 cells of the tricellular model of atmospheric circulation

• Polar Cell - Descends at 90, Ascends at 60

• Ferrel Cell - Ascends at 60, Descends at 30

• Hadley Cell - Descends at 30, Ascends at 0

High pressure at 90 and 30 degrees (Less Clouds)

Low pressure at 30 (Clouds) and 0 degrees (Inter tropical Conversion Zone)

Enhanced greenhouse effect

The accumulation of GHGs (Greenhouse gases) by human activity leading to global warming - increasing mean global temperature

Climate Change

Encompasses global warming but refers to the broader range of changes that are happening to the planet as a result.

What causes the greenhouse effect?

Greenhouse gases (GHGs) absorbing and re-emitting infrared radiation, which is given out by the Earth’s surface after being warmed by the Sun.

Greenhouse effect

A natural phenomenon responsible for creating a habitable temperature on the Earth. (Increase by 30*C).

The Earth’s temperature depends on the concentration of GHGs in the  atmosphere. 

Source of Carbon dioxide

Released as a result of respiration and combustion and mitigated by plants through photosynthesis.

Source of Methane

Produced by livestock, agriculture and wetland microbial activity.

Source of Nitrous oxide

Produced by industrial activities, and fertilisers.

Source of CFCs and HFCs

From refrigeration and aerosols.

Source of Black carbon

from incomplete fossil fuel burning - contribute more to climate change than previously thought.

Water Vapour

• the most common GHG

• creates a positive feedback loop by increasing warming and evaporation

• Excluded from climate models as its abundance changes as a result of global warming

• Dynamic within the atmosphere and essential for life

• Cannot be mitigated against